1. Field of the Invention
The present invention relates to vibration and mechanical shock protection of electronic devices, and more specifically, to a method and apparatus for providing a fluid damping structure with fuel cell for a hard disk drive or other sensitive electronic device used in high vibration and shock environments.
2. Description of Related Art
The increasing popularity and computing performance of portable electronic devices such as cell phones, MP3 players, global positioning units, PDAs and portable computers, coupled with the miniaturization and increased storage density of hard disk drives, has migrated demand for the hard disk drive into these portable devices. However, the hard disk drive was never designed to be used in high vibration or high impact and shock environments. Redesigning the hard drives to meet such requirements would increase costs and reduce demand for many portable, cost sensitive applications such as cell phones and MP3 players. It would be useful to have a packaging system that would isolate currently designed drives from shock and vibration to enable such drives to be used in portable devices.
Shock-absorbing materials can be made from a mixture of solid particles and viscous elastic material and arranged at the periphery of an information storage and retrieval device. When an external shock is applied to the device, the shock-absorbing material is greatly deformed and dissipates the shock energy by inner friction sufficiently to prevent damage to the inner mechanism of the device. The deformed shock-absorbing material can be restored to the original shape so that it is repeatedly usable. However, the shock absorbing material disclosed in the aforementioned references requires that the storage device be manually repositioned to its original position after impact. This is impractical in most potable device applications because users usually do not open their cell phones or MP3 players after they are shocked or dropped, due to the difficulty of opening such miniature devices. Often, the manufacturer discourages such action by voiding warranties. The shock absorbing materials are complex solids containing a wide variety of components including sand, springs, complex webs, and cloth contained within a solid viscous elastic material. These materials may be expensive to manufacture, increasing the potential cost of the hard drives and reducing the desirability for their use in mass-produced portable applications. Additionally, it is unclear as to whether the disclosed structures are effective for isolating vibration, which may be just as destructive to the hard drive if present over prolonged period of time.
In addition, cushioning devices may be placed at the four corners of a hard disk drive to suspend the drive within an external frame. Such cushioning devices may be composed of various types or rubber or solid viscous elastic material such as silicone gels. However, the area supported by the cushioning devices is limited, which may create compromises between shock protection and vibration isolation. Thus, a stiffer material that can transmit more vibration is required to protect effectively against shock loads with cushioning devices having a small contact area.
In addition to the problem of overcoming shock issue with portable electronic devices such as disk drives, power supplies of one sort or another are ubiquitous in such devices. Perhaps the best-known portable power supplies are batteries, of which there are many types and kinds. Batteries are very versatile power supplies in that they are typically able to power several times their optimum load for short periods of time. Indeed, the average lifespan of a battery is largely dependent upon the duration of its use, in combination with the size of the load applied thereto. Rechargeable batteries are also known, and they differ only slightly from conventional non-rechargeable batteries in that they may be periodically re-energized via external sources.
Despite their inherent versatility, batteries (both primary batteries, as well as rechargeable batteries) have a limited lifetime and usefulness, and must be replaced or recharged periodically. Thus, operators of high-load electronic equipment often carry several back-up batteries to address the extended operation of their equipment.
Fuel cells are also known power supplies, and are able to produce electrical power from the interaction of a fuel stream, typically consisting of hydrogen gas or the like, and an oxidant stream that contains oxygen. Other types of fuel cells, utilizing different fuel and oxidant streams, are also known.
In the past, practical applications for fuel cells have largely focused on large-scale uses such as stand-by power systems, and automobiles. This is due to the volumetric inefficiencies of fuel cell power plants, which are typically large in size. Thus, fuel cells are not currently considered as viable power supplies for wide-scaled application for small-scale electronic devices and appliances. Yet, companies are making large investments into fuel cell for this very reason.
Fuel cells are typically designed within demanding parameters. That is, fuel cells are designed to address specific size, weight and performance criteria. In contrast with batteries, fuel cells have typically been designed to provide power only marginally above their nominal level, and then for only short durations. If asked to exceed their nominal power output, fuel cells exhibit the characteristic of constant power supplies in that they will typically reduce their voltage output in accordance with Watt's law, addressing a higher current demand by supplying a corresponding lower voltage until such a time that the voltage is no longer capable of powering the load/electronic device.
In spite of the limitations discussed above, there is conceivably a wide range of products that would benefit from the use of fuel cells as a power supply. For example, in those applications where the electrical device is operated for extended periods of time away from a landed AC power source, it is often necessary to carry large amounts, and differing kinds, of batteries and/or associated recharging devices. One benefit of fuel cells, despite their volumetric inefficiency, is that the fuel itself (apart from its converter apparatus) can be carried in relatively smaller and lighter containers versus carrying the equivalent power in batteries.
Direct methanol fuel cells have become extremely promising as a power source for use in portable electric and electronic appliances. Direct methanol fuel cells generate power from methanol by removing protons directly from the methanol. This operates without using liquid acid or a reformer, and has many benefits including a bio-renewable fuel source, and virtually no undesired pollutants as output. One of the applications of such a fuel cell is for use in powering portable electronic equipment, such as laptop computers and cellular telephones and the like.
However, the fuel cells require a source of energy. For example, in a direct methanol fuel cell, methanol is typically supplied in cartridges, which could be inserted into the electronic device, and used to power the electronic device. When the cartridge is empty, the cartridge is replaced with a new cartridge, typically a cartridge that is readily available. In this way, the user can use the cartridges in place of batteries. However, a Is cartridge contributes additional weight to the portable devices.
It can be seen then that there is a need for a method and apparatus for providing a fluid damping structure with a fuel cell for a hard disk drive or other sensitive electronic device used in high vibration and shock environments.